To handle tubular products such as flush joint pipe and drill collars at the floor of a drilling rig, a clamp apparatus is employed that provides one or more shoulders by which the pipe can be elevated and lowered. One mechanical device that has been used includes hinged slips which surround the pipe and grasp the same, and a latch structure providing a gate which is opened to position the clamp around the pipe and closed to lock the clamp in place. The latch structure includes a long bolt having a thrust washer slidable thereon so that it can be positioned against the arms of the latch, and an adjusting nut that is threaded on the outer end of the bolt adjacent the washer. After positioning the assembly of linked slips around the pipe, the gate is closed by pivoting the bolt to position the thrust washer and nut in alignment with the latch arms. Then the nut is tightened by hand using a large wrench, and a sledge hammer, to bring the washer up tightly against the latch arms to close the gate and create hoop stresses that cause the slips to grip the pipe. An example of this type of device is shown on p. 8426 of the "1982-83 Composite Catalog of Oilfield Equipment and Services" published by World Oil.
Although this device has been used for some time, there are many dangers inherent in hand operation of most any device that is used on a rig floor to handle heavy masses. If the gate is not properly closed, latched and tightened, the pipe can be dropped and cause serious injury, particularly to a worker who is near the area by virtue of having manually positioned and closed the clamp.
The general object of this invention is to provide a new and improved clamp apparatus for handling tubular products in a safe and reliable manner.